1) Field of the Invention The present invention relates generally to a superconducting magnet apparatus, and particularly to a superconducting magnet apparatus that is freely orientable and portable.
2) Background of the Need
For many current superconducting magnet applications, weight is typically not a major design criterion because they do not need to be mobile. Existing superconducting magnet systems often have the liquid cryogens (and storage means) as an integral part of the magnet cryostat. Systems that have the cryogens stored separately from the magnets are typically stationary and may not allow free orientation of the magnet with respect to gravity.
As superconducting materials mature, (e.g. higher temperature operation and current density, smaller size), their weight and cost will decrease thereby opening up new or expansion of existing opportunities. A light-weight, portable magnet (“field deployable”) that could be oriented in any direction could have applications for temporary deployment of military or civilian medical facilities for use with MRI or NMR machines. For example, such field-deployed MRI or NMR machines could be used at the scene of accidents or in homes where a patient is not movable. A concern with current MRI machines is the claustrophobic effect where some patients simply can't endure the procedure without sedation. Children become terrified and are inconsolable by parents. There is a need for an open framed MRI machine. Multiple (flowed cryogens) coils could allow for an open frame MRI configuration. The open frame alleviates claustrophobia, permits contact with the patient, and permits diversions such as television or movies. A freely orientable high-field magnet with separate cryogens would allow cranes, specialized laboratory lifting devices, and machining chucks to connect (magnetic coupling) to metal objects. A freely orientable portable magnet could be moved to and provide an external magnetic field to magnetize various ferretic objects. Two opposing magnets could be coupled together to produce lifting devices for large objects in emergencies or specialized industrial applications. There is a need for a superconducting high field magnet that can be operated in any orientation relative to gravity, and is portable (preferably operable and each subassembly transportable by one person due to its low weight and size).
3) Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Superconducting magnets require cooling systems to maintain the conductors at superconducting temperatures. Cooling may occur via one or more methods: thermal conduction, radiation or convection. Systems that utilize coolant for convection cooling generally fall into two categories. One category provides for immersing the conductors in a pool of coolant. This mode of cooling limits orientation of the magnet. The second category provides for circulating coolant through or in channels near the conductors. The coolant may be single phase (gaseous utilizing sensible heat) or two phase (utilizing latent and sensible heat).
U.S. Pat. No. 4,048,437 discloses cooling superconducting magnets via circulating coolant in conduits in which the conductors are disposed. U.S. Pat. No. 4,692,560 discloses a superconducting coil apparatus wherein the superconducting wires are cooled via coolant flowing through the conduit in which the wires are disposed. U.S. Pat. No. 5,317,879 discloses using cables to cool superconducting magnets via thermal conduction. U.S. Pat. No. 5,402,648 discloses a system for cooling superconducting magnets via circulating coolant from a dewar. U.S. Pat. No. 5,442,928 discloses cooling superconducting magnets by circulating liquid helium. U.S. Pat. No. 5,461,873 discloses natural convection cooling of a superconducting magnet by circulating helium gas. U.S. Pat. No. 5,485,730 discloses cooling superconducting magnets via circulating coolant from a remotely located cryocooler. U.S. Pat. No. 5,495,718 discloses cooling superconducting magnets via circulating coolant from a closed dewar. U.S. Pat. No. 5,848,532 discloses cooling superconducting magnets via circulating coolant remotely from a remote cryocooler. U.S. Pat. No. 6,107,905 discloses a superconducting magnet apparatus wherein cooling occurs utilizing the latent heat of vaporization of liquid helium.
Superconducting magnet apparatus require support structures to prevent movement of the conductors that may create friction causing quenching of the superconducting state.
U.S. Pat. No. 5,446,433 discloses a support structure for a superconducting magnet which is resistant to shock and vibration forces. U.S. Pat. No. 6,078,234 discloses structural members to resist forces generated within and between pairs of superconducting magnetic assemblies. U.S. Pat. No. 6,011,454 discloses a suspension system, comprising frustro-conical surfaces, for a superconducting magnet assembly.